Flexible conductive members are pliable and can be flexed or shaped to meet particular application requirements. Flexible conductive members have been of particular importance to the medical community wherein patients often need to be connected to electrical monitoring or electrical generating equipment. In such applications, flexible conductive members such as return electrodes need to adapt to the shape of the patient's body in order to provide the required surface electrical contact.
Electrosurgery requires an electrosurgical generator connected to at least two electrodes to produce and deliver an electrical potential to a patient's tissue. In monopolar electrosurgery, the electrodes usually consist of an active electrode applied at the surgical site and a return electrode or pad applied to a non-surgical site on the patient.
Return electrodes are flexible conductive members and are usually manufactured to attach with a pressure sensitive adhesive directly to the surface of the patient. Return electrodes are therefore designed and manufactured to be form fitting or flexible so as to provide adequate conductive contact with the non-flat surfaces of a patient. There is typically a conductive adhesive to hold the return electrode to the patient.
Return electrodes need to be electrically connected to the source electrosurgical generator. This connection is usually provided by way of one or more insulated conductive wires which are configured to interface with the electrosurgical generator and complete the circuit. The physical connection between a wire and the return electrode must not only provide an adequate and stable conductive interface, but must also provide adequate strain relief characteristics to withstand potential mechanical forces applied to the insulated wire and/or return electrode.
Contemporary wire termination methods usually require that the ends of a wire be stripped of insulation, formed, and assembled to the flexible conductive member with a staple shaped attachment or some other attachable fastener such as a circular terminal and a rivet. The stripping process is highly dependent upon the nature of the insulation of the wire, the strip tooling design, and the tooling setup. Wire stripping problems generally result in broken wire strands or wires that cannot be formed or terminated properly in subsequent operations. Uncontrollable variables in the existing terminating process, such as those, can result in marginal or inadequate electrical and mechanical connections. Inadequate electrical connections resulting in termination impedance changes may negatively effect the performance of the overall electrosurgical system, particularly when the electrosurgical generator includes, as many do, dedicated return electrode monitoring circuitry.
In order to maintain product specifications and meet production goals, the return electrode assembly equipment must be monitored and adjusted frequently to account for the varying properties in the raw materials, especially to account for variations in the insulation characteristics of the wire.
The method, terminal and assembly described herein eliminate the need to prepare either the insulated wire or the flexible conductive member prior to assembling them. The method, terminal and assembly overcome problems with deviations found in the production of wire conductors and insulation. The method, terminal and assembly provide a low impedance electrical connection and an strong mechanical interface between the insulated wire and the flexible conductive member.
U.S. Pat. Nos. 4,679,880, 4,995,827, 4,669,801, and 5,091,826 include connectors having insulation displacement members. Each of these connectors provides an interface between an insulated wire and a rigid member such as a printed circuit board, and requires a separate clamping element to provide a stress relief by holding the wires against the insulation displacement members.
U.S. Pat. Nos. 3,950,065, 3,937,549, 4,074,929, and 5,022,868 have connectors with several insulation displacement beams or members that, when mounted on a rigid body such as a printed circuit board, provide places for electrical and mechanical interface between the body and an insulted wire. To connect an insulated wire with these connectors the wire is forced into an insulation displacement channel or opening whereby either a portion of the channel deforms, or other wire engaging elements contact the wire, to secure the wire in place.
The insulation piercing terminal connector disclosed herein can be forced through a flexible conductive member, and into and around an insulated wire in a single mechanical process. The assembly produced by this process is partly similar to that of a standard metal staple used to hold pieces of paper together. Unlike standard single wire insulation displacement connectors, the piercing members disclosed herein, which may form a conductor engaging channel, may pierce into the insulation rather than slice into the insulation. These piercing members provide a smaller overall package while also allowing a nearly gas-tight seal with the conductor and insulation.
The insulation piercing terminal and its piercing members also act to enhance user and/or patient safety by allowing the piercing members to be exposed during assembly and shielded thereafter. Thus, the piercing members of the assembly are active when required and harmless when in use. This safety feature is unknown in the prior patents.